Manufacture or treatment of steel armor-plates.



STATES PATENT OFFICE. I aoBERT A. HADFI-ELD, or SHEFFIELD, ENGLAND. MANUFACTURE en TRATNlENT OF STEEL ,ARNIOR-PLAITEZSI Specification ot Letters Patent.

' Patented new. 6, 1906.

, Application ma A rl114,1906. sol-also. anflaa.

To all whom it may concern: r

Be it known that I, ROBERTA. HADFIELD,

a subject of the Kin of Great. Britain, and a resident of Shefliel countyof York, Eng-'- land, have invented an Improvement in the Manufacture or Treatment of Steel Armor- Plates and the Like, of whichthe following description, in connection with the accompanying drawing, is a specification, like letters on the drawing representing like parts.

This invention has for its object theproduction of an improved process or mode of treatment for cast-steel armor-plate shields and the like with plain, corrugated, or other faces, and the invention can be applied to the treatment of other articles of steel, whether or not having hard surfaces. In apending application, Serial No.'283,235, filed b me- October 18, 1905, I have describe an improvement in the manufacture of cast-steel armor-plates with corrugated faces. The present ap lication is an improvement for carrying orward the method or process of treatment therein setforth. 11 carrying out my resent invention I have'in ractice obtaine satisfactory results by the ollowing mode of procedure: A mold is prepared from a attern of appropriate dimensions and of t e proper form, and said 'mold can be made of fire-resisting sand dried in the usual manner. Upon one of its edges he article to be produced being prefera ly cast verticall the head or fee ing ortion is located; he metal used may a vantageously be steel prepared in-a manner similar to that described in the specification of my British Letters Patent No. 16,132, of 1901. After pouring, and preferably while the casting is still hot, it is removed to a furnace, where it is allowed to ,cool down slowl in order to prevent internal strains, after w 'ch the sand is removed and the casting carefully cleaned.

In the caseof a shield, plate, orother arti cle, whigh I shall hereiria ter'refer to for tlbie sake of revit as a p ate, re to e rendered hard on one or more (if its surfaces such late is suitably carburized where .re- 7 uire For example, the plate is put into a urnace, and u on the surface of the plate is placed a suite. 1e carburizing medium, such as charcoal. The temperature of the furnace is then raised to, say, between 900 centigrade and 1,100 centigrade', and the plate is allowed to remain in the furnace for several days, the actual period in a given case depending upon the extent to which the carurizin is to be carried. The plate is then allowe to gradually cool down in the fur-.

nace, and the head or riser is removed in the usual manner by being slotted off. I then heat the plate to from 700 centigrade to 850 centigrade, usuallypreferring about 760 centigrade, after w oh the plate is cooled down as far as desired, either slowly in the furnace or it may be air-cooled, and it is then res 4 heated to between 700 centigrade and 850 v centigrade and cooled to between 640 centi-i grade and 690 centigrade, after which the plate is wholly or partially quenched in water, de ending upon the size and shape of the'ar-' tic e, due care be' taken that the plate is not allowed to remain toolong in the water to produce a greater degree of'hardness or stiffness than required. After this quenching the plate is again heated to between 57 0.cen-

tigrade and 640 centigrade, the preferable temperature depending upon the composi-. tion of the steel, and it is allowed to cool in the furnace. It is then reheated to between 570 centigrade and 640 centigrade and quenched outright, preferably in water, after which 'it may be taperheated-that is, heated so that the face assumes a temperature of from'700 centigrade to1770 centigrade, tapering .to a temperature at the back of the plate o from 400 ,centigradeto 600." centigradewhereupon the plate is dipped in or s rayedwith oil'or water, accordingto the har ness required. Inasmuch as the face is hotter than the back, the face will become hard, while the back remains soft andtough; I

1 In some cases-as, for example, when a very soft steel is being treated, 11.0., one low in 'carbon-ra uniform instead of a taper heating ma be adopted.

f the plate does not require. to be'facehardened, the carefully-cleaned" casting is h temperature -say 900 centigrade and 1, 1 00 centigradet he plate being withdrawn laced in a furnace, which is then raised to a 4 from the furnace as soon as the requisite temperature f has been reached. The head or riser'is then removed. 1 3

The remaining steps in the treatment for a plate that is not-face-hardened are the same as for a face-hardened plate, 'as' hereinbeforeset forth exceptv that the taper-heating -is omitted when producinga plate that is not face-hardened.

- The heat treatment hereinbefore described,

with or without carburization and with or forth may be more or less modified in dif ferent particulars by those skilled in the art', without departing from the spirit and scope of my invention.

olacimas new, Patent, is-

(1. in the manufacture of steel amor- 1 ,plate, shields and the like, gradually raising to 850 centigrade-and-cool-ing slowly-and reheating to between 700=cent1g1=adeand 850 Centigrade, and needing to between 640 oen ti'grade and 690 centigrade, and quenchreheating latter quenching to between A 570 mentigrade :and 640 centigrade and l reheating to cooling; re siting the hea to not more than *640" n e ntigrade, and th di quendring. phi In the manufacture 'of steel armorte, the it a. the articlie-to (time11:11- 900 centigraeto 1,100 'centigra ean a owing the article to gradually cool down; then heating said article to from 700 'centigm-de to 850 centiglrade' and cooling slowl and etween 700 oentigra e :and 850 'oentigrade and cooling to between 640 oentigrade and 690"centigrade,-and quenching; reheating after quenching to between 570 *eentigrade and 640 scentigrade and coeling; mepeatisng the heating to not more than 640 oentigrade and then quenching; then taper-heating the article, raising the temperature of the face thereof higher than the temperature of the back, and dipping or spraying with oil -or water.

3. the manufacture of steel armor, plate, shields and the like, subjecting the 7 plate to a temperature of from 900 centishields and the like, gradually maising grade to .1,100 centigrade While the face thereof is in contact with carbonaceous ma- 'teria'l, and maintaining the plate subjected to such temperature for several days; then allowingt'he plate to radua'lly cool down; reheatin it to from 700 centigrade to 850 centigra e and cooling slowly, and reheating to between 700 centigrade and 850 centi- Having described my invention, what I and desire to-secure by Letters grade and cooling to between 640 centigrade and 690 centigrade, and uenching; reheating a'fter quenching to I etween 570 .centigrade and 640 oentig-rade and cooling, .repeat' the heating to not mere than 640 oent' e, :and then quenching.

' 4. he herein-described process of making steel minor-plate, shields and the like, whic consists in casting the same in a mold, slowly cooling the casting in a furnace, and thereafter removing and cleaning the casting; subjecting the casting for several days to a furnace-temperature of from 000 centigrade to 1,1'00 cem1tigrade while in contact with carbonaceous material, land rthen allowing the plate to gradually cool down in the humane; then heating the to from 700 centigrade to 850 oerrtignde and 0001- ing slowly; the last-named step and then cooling the casting to between 640 cent we and 690 .oentigrade, and quenchmg coasting in water; meheozt mg to between 570 centigrade and 640 oentigra and cool" mepeating the last-named heating, and t enquenching the casting; then taperr'heating su'c'h 'casting'te a temperature of from 700 centigrade to 770 centigrade at its face, tapering to from 400 centigrade \to 600 centigradeat the back, and or spraying with -oil or water.

In testimeny whereof I have signed my name to this specification in the'pu'esence of two subscribing witnesses. 

